1. Field of the Invention
The present invention relates to a process for the preparation of a motor coil, particularly a motor coil which is penetrated and retained by a column-shaped motor core and in which a ribbon conductor is disposed such that a width direction of the ribbon conductor is extended in a radius direction of the motor core and the ribbon conductor is helically superposed on one another in an axis direction of the motor core and along an outer peripheral surface of the motor core, and an apparatus for the preparation of the motor coil.
2. Description of the Related Art
For instance, a motor coil which is retained by a column-shaped through motor core and in which a ribbon conductor is disposed such that a width direction of the ribbon conductor is extended in a radius direction of the core and the ribbon conductor is helically superposed on one another in an axis direction of the core and along an outer peripheral surface of the core, has been already suggested. The motor coil is referred to as a longitudinally wound motor coil.
FIG. 11 and FIG. 12 are views for explaining a process for preparing the longitudinally wound motor coil. In the conventional process, first a block 101 composed of copper or aluminum is prepared as one body by extrusion molding, and a helical groove 104 is formed on the block 101, the groove 104 reaching from an outer peripheral surface 102 of the block to a hollow part 103 of the block, whereby a helical electric current path is formed.
In more detail, as shown in FIG. 11, a rotating cutting tool 110 moves in the direction of the arrow, and forms a straight groove 104a on the block 101. The groove is formed at same intervals so as to have necessary winding number. Thereafter, as shown in FIG. 12, the locations of the block 101 and the cutting tool 110 are changed relatively, whereby a straight groove 104b is formed. Beginning and end points of the groove 104b are obliquely connected with the groove 104a to form the helical groove 104 on the block 101. Further it is already known that the grooves 104a and 104b are simultaneously formed by using the cutting tools 110 of the same number as that of the grooves arranged in a row (see JA07-163100).